The invention relates to a feed-through element for application in a vacuum apparatus for the continuous feeding through of material with wire character to be treated at least made up of a casing and a sealing element set up therein that is in contact with the surface of the material with wire character during feeding through.
Such feed-through element is known from British Patent Specification No. 1,428,933. In said publication is described a tubular feed-through element, which can be inserted in the external wall of a vacuum treatment apparatus or in the partition walls located between the different compartments of such apparatus. Said tubular feed-through elements consist of a casing and also of bored end flanges through which the wire-shaped product to be treated can be fed. Inside the casing there are bored sealing elements of material with a low friction coefficient and/or a good heat resistance, the bore being such that the outer surface of the wire-shaped product to be treated fits closely to the inner surface of the bore.
The term of "vacuum treatment" is in the present application to be understood as referring to every treatment of a material with wire character that takes place in a vacuum environment, such as vacuum deposition, sputtering, plasma precipitation, ion implantation, heat treatments, plasma cleaning, etc.
"Products with a wire character" is to be understood as referring to both single wires and composite wires such as cords or ropes.
A known feed-through element as described hereinabove has the disadvantage that the elements which fit closely around the material with wire character thereby forming a seal are subjected to very high wear, that such wear can show itself in a contamination of the surface of the material fed through and that in the course of time the sealing effectiveness of the sealing elements decreases.
Furthermore, serious damage to the sealing elements may occur in the case of a sudden thickening in the material with wire character, for instance, there where wires have been welded together and where there is still a weld thickening or part of it.